Question

I have a requirement to create a 3-Dimensional ArrayList.

  ArrayList<ArrayList< ArrayList<Object>>> data_Header_Mapper; 

How can i populate the 3 D arraylist and how i acccess the leaf child ( Object) of 3 Dimensional ArrayList. Lots of thanks in advance for any help.

I am familiar working with Vectors , But due to some problems i want to convert the below code of Vectors to ArrayList.
Code For Populating 3 D Vectors is as follows.

  for (int r=0;r<totalRows;r++) // r - Rows
   {

     for (int c=0;c<totalViewedCols;c++) //c- Columns
     {

       cAct=0;
       while (cAct < totalActualCols)
      // for (int cAct=0;cAct<totalActualCols;cAct++) //c- Columns
       {
         if (Cols.get(cAct).toLowerCase().equals(columnName.toLowerCase())  )
         {
          ColValindex =  colHeader_ForSave.indexOf(columnName)  ;//Temp Comment
          colValue= (String)data_ForSave.elementAt(r).get(ColValindex);
         //  ColValindex =  header.indexOf(columnName)  ;
         //  colValue= (String)data.elementAt(r).get(ColValindex);

           data_Header_Mapper_Element.add(columnName); 
           data_Header_Mapper_Element.add(colValue); 
          }
         cAct++;
       }
       if (data_Header_Mapper_Element.size() !=0)
       {
        data_Header_Mapper_Row.add(data_Header_Mapper_Element);
       // data_Header_Mapper_Element.removeAllElements();
      data_Header_Mapper_Element =null;
      data_Header_Mapper_Element=new Vector<String>();
       }
     }
      if (data_Header_Mapper_Row.size() !=0)
     {
       data_Header_Mapper.add(data_Header_Mapper_Row);

       data_Header_Mapper_Row =null;
       data_Header_Mapper_Row=new Vector<Vector<String>>();
      }

   }

Code For Access 3 D Vectors is below

  for(int r=0;r<rowSize;r++)
      {

      for (int c=0;c<colSize;c++)
      {

      // To Build Insert And Update Query 
           columnDataType=  dbe.GetDataTypeOfTableColumn(rsMetaData,data_Header_Mapper.elementAt(r).get(c).get(0).toString());
           dataSize=dbe.GetDataSizeOfTableColumn(rsMetaData,data_Header_Mapper.elementAt(r).get(c).get(0).toString());
           Validation.ValidateData(columnDataType, data_Header_Mapper.elementAt(r).get(c).get(1), dataSize);

         }

        }

Answer 1

public class My3DArray {

    private List<List<List<Object>>> list;

    public My3DArray() {
        this.list = generate3DArray(5, 5, 5);
    }

    public List<List<List<Object>>> generate3DArray(int dim1, int dim2, int dim3) {
        List<List<List<Object>>> list = new ArrayList<List<List<Object>>>();
        for(int i = 0; i < dim1; i++) {
            List<List<Object>> list2 = new ArrayList<List<Object>>();
            for(int j = 0; j < dim2; j++) {
                List<Object> list3 = new ArrayList<Object>(dim3);
                list2.add(list3);
            }
            list.add(list2);
        }
        return list;
    }

    public Object getElementIn3DArray(int i, int j, int k)
        throws NullPointerException, ArrayIndexOutOfBoundsException {
        return list.get(i).get(j).get(k);
    }

    public void setElementIn3DArray(Object o, int i, int j, int k)
        throws NullPointerException, ArrayIndexOutOfBoundsException {
        list.get(i).get(j).add(o);
    }
}

public class Main {
    public static void main(String[] args) {
        My3DArray x = new My3DArray();
        x.setElementIn3DArray("Hello World", 0, 0, 0);
        System.out.println(x.getElementIn3DArray(0, 0, 0));
        System.exit(0);
    }
}

I omit some variables in the class like the dimensions but this is an idea. Its up to you how to use this example.